Crystallization of titania in liquid media and photochemical properties of crystallized titania

Titania gels in liquid media crystallized from amorphous to anatase at temperatures as low as 120 °C, while the onset of crystallization in air was 370 °C. The crystallization rate in water was much faster than in methanol and n-hexane, and the crystallite size of anatase prepared in water was larger than of those prepared in organic solvents. The crystallized powders were capable of efficient hydrogen evolution following band gap irradiation in the presence of a sacrificial hole acceptor such as methanol. The photocatalytic activity of powder crystallized in methanol was superior to those prepared in water and air.